A safety message dissemination method in a travel guidance system.

In the past studies, a road accident message was often broadcast by forming a Vehicular Ad Hoc Network (VANET), in which the safety message broadcasting methods often lead to broadcast storms. This study presented a method to broadcast accident messages in a travel guidance system (TGS) that avoids broadcast storms that avoids the need for vehicles to form an ad hoc network. Unlike most current methods, which disseminate messages to as many vehicles as possible, this method sends messages only to the exact vehicles that will be influenced by an accident. In the TGS, the transport center of a city sends messages of the optimal routes and alternative routes to travelers when they start their journey. In normal situations, vehicles run on the optimal routes determined by the transport center. When an accident happens in a street, the accidental vehicle sends a message to the transport center through 5G communication. The transport center looks up the vehicles with their original routes passing the accident location during the lasting time of the accident and sends a safety message to them. The influenced vehicles then select the alternative routes which are stored in their On-Board Unit (OBU) to avoid the accident. Vehicles not influenced by the accident receive no message. Thus the redundant and unnecessary dissemination of messages will be removed. The method presented in this paper is the only one that can thoroughly remove the unnecessary and redundant rebroadcast.